<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <title>3-8 vm.$el</title>
</head>
<body>
<div id="app">
  <p>I am a root tag construct</p>
</div>
</body>
<script src="./js/vue.js"></script>
<script>
  var vm=new Vue({
    el:"#app"
  })
  vm.$el.innerHTML="<div>I am a tag of after the replacement</div>"
</script>
</html>